Dynamo-electric machine.



0 0. MITCHELL. DYNAMO ELECTRIC MACHINE. APPLICATION FILED NOVV, 7, 1911.

v Patenm dm .23',-1912.

CLARE/v05 C. M/TcHEiL UNITED STATES cmnncn 13011121 1 ELECTRIC COMPANY, A CORPORA ION or oHIo.

ynamo- Macrame MACHINE.

MITCHELL, OE'MADIS'ONVILLEI .oino, ASSIGNOR' PATENT OFFICE."

To THE TRIUMPH Application filed November-7, 191 i. s erial No. 658,980.

To alZwIi-om'z't may concern:

Be it known that I, CLARENCE ,"Conn'm Miro En'L, a citizen of the United States,

residing at Madisonville, the county I of Hamilton and State of Oh10, l1&V$ invented certain new and useful Improvements ,.'.-1n

Dynamo Electric Machines, ofv which the following is a"full," clear, and exa'ctspecifi: cation; I This invention relates tobrac kets for supporting the rotatable'elements of .eletrid generators or"motors.- r

Theobjectis to provide means for accu} rately centering the rotary:eleme'nt. iThe air gapjbetween the field poles or stator and the armatureor rotor of such machines is made assmall as is consistent with a goodmechanical operation to decrease asmuchas possible the reluctance ofthe magnetic clrcuit-and produce a maximum torque or current. With machines of induction type,

particularly such as induction motors, the air gapis very small and it is important to provide for and maintain a true central relation of the rotor/With respect to the stator.

This centering isordinarily determined by" drilling a group of'symmetrical holes in the end-cap orbracket in which the rotor-shaft is journaled' and sliding the bracket in place over stud-bolts similarly spaced in the end wallsv'of the stator frame tor yoke. As an eccentricity of the rotor with respect to the stator'of' one one-thousandth of an inch materially, affects the performance of the motor, itis desirable to provide a more per fect means of centering than that ordinarily employed. My invention permits the endto 'be attained with a great degree of accuracy; I

In carrying out the invent-ion I' provi,de the central bracket. at a plurality of points adjacent to the rim with elongated slots extending'in a line coincidentwith' a chord ofan are and employ tapering adjusting screws mounted the Walls of the -bracket to expand the slots. 'The bracket supported over a plurality-of stud-bolts mount ed on the end of the stator frame and enters a circular recess machined in said frame to 7 approximately center 1t.- After belng as-- sembled adjustment of one or ,more of the 'scr'ews'expands its slot and shifts the rotor in a desired direction to accurately center it inthe magneticfield of the stator, rendering the Width of the air-gap perfectly-uni f form throughout. The slots are formed near-the periphery of' the centering bracket ,Wlll0l1 permits its wallsto springslightly so g tqghiftthe r'otor in the desired direction- 111 the, stator'yoke. 1 I i its axial ,center'on its supporting studs into 7' true central alinement the stator field. v I

It consists also of other more specific featuresv which will be hereinafter fully described in the specification and definitely in- "dicated inlthe claims;

- I1 1.-.th'e accompanying Y drawings [which illust atetheinvention Figure I is a rear elevation of a supporting-bracketfembody ing my improvements. Fig. 2 is. a'sectional View along radii onthe line 22'of Fig. 1. Fig. Sis aside eleyationof a portion ofthe bracket on a planeat right angles to that of 'Fig- .1.

I Referring ith the center of now to'the drawings in detail,

Fig. 1" represents a bracket. embodying my improvements-formed as a casting with a plurality of radial arms Qand a central hub 3 to receive a bearing for the rotor shaft. Near the rim of the bracket are drilled a plurality of holes 4: symmetrically.related and adapted to slip withsuitabl'e clearance over similarly spaced stud-boltslO on the circular endof the stator'5. I have shown four of these holes, although, of course, a

greater or clesser number might be employed] "I preferably place between each 'pair of these holes a'slot- 6 milled inthe 'cas-- ing and of a length subtending an are near the periphery, the slots extending close to the edge .of the'bracket, as indicated in the drawing. The Walls ,of'ftlie bracket are thickened at the center of the slots so as to form bosses which may be tapped toreceive adjusting 1 screws -7 The end of these screws as indicated-at 8 tapers and the Walls of the slot are widened at the central point.

(see Fig. 1) to admit the tapering end.

In assembling the parts a bracket suchas is described is .placed at each end of the with some clearance, the machined periphery- 9 of the bracket in the cooperating recess on the end of thelstator. 1 One or more of the the opposite direction.

screws 7 are then adjusted in the slots 6 so as to bring the rotor truly central wi1hin the stator field, by expanding the slot and shifting the bracket in the desired direction to produce a concentric relation. The adjustment required is very slight, and .the springing of the outer wall of the slot forces the periphery 9 against the wall of the re cess in the stator frame 5 as an abutment therebyshifting the body of the bracket in. I If overadjustment is produced the diametrically opposite screw will permit compensation in one diametricalline, and adjustment of the slots cnthe diametrical line at'right-angles will permit a true centerto be obtained. After definitely finding the center, the bracket is screwed tight on the rotor frame by lock-nuts engaging the stud bolts passing through the holes 4t. It will be evident that if the rotor,

gets out of centdr at any time, the eccentricity may be easily corrected by suitable adjustment of one or more of the screws 'Z.

The "invention, while of especial use in electric generators pr motors, s of general advantage and may housed on any type of rotary machines on which small clearances exist and where accurate centering is necessary.- j Having thus described my invention what I claim as new and desire to secure by Let 1. Means for centering the "revolving element of a rotary machine 'corn'gwisingaframe, a bracket secured to said :ri'ame and adapted-to support said element, said bracket ha ving a rimcapable of lceing ex panded, and means for-expanding the rimat a plurality of peripheral points to shift the rotary element into true centrality.

2. Means for centering a rotary element comprising a bracket adapted to supportsaid element and having a'plurality of slots near its rim,- and adjusting'screws for expanding theslots.

Means for centering'a rotary element comprising a circular bracket adapted '-to support said element,. a cooperating fixed element-{said bracket beingsymmetrically seated against a part ofthe cooperating fixed element and-havinga pluralit-y of slots near itsrim, and tapering screws'for expanding "the slotsr r 4. Means for accurately, centering a rotary element within its cooperating. stationresales ary element comprising a stationary element,

a supporting bracket-seated in a circular recess of the stationary element and having a plurality of' slots near its rim, and adjust .ing screws for expanding the slots.

5. Means for centering a rotary element within-a stationary element comprising a stationary element, a circular bracket mount- .ed on studs on the end of the stationary element and having a plurality of slots near its rim, adjusting screws to expand the slots, and an abutment on'the stationary element to engage the outer slot walls.

6. Means-for'centering a motor armature comprising the field magnet frame. an end bracket mounted in a circular recess in the field magnet franie, said bracket having a plurality of slotsncarits rim. and tapering adjusting screws on the bracket to expand the slots. r 7. In a dynamoelectric machine. incl osing means consisting of a stator frame with faced ends and faced end shields provided with bearings for the rotor, one of the inclosing parts having rigidly attached elastic centering portions engaging the other part, means for springing the centering portions, and means for clamping together the parts of the inclosing means, substantially as described. Q g 4 8. In a dynamo-electric machine. a stator frame with faced ends, faced end shields provided with"bearings'for the rotor and elastic centering portions rigidly attached thereto and engaging the stator" frame. means for springing the centering portions and means for clamping the end shields'to the stator frame, substantially as described.-

9. In a dynamo-electric machine. a stator framewith faced ends, faced end shields provided with bearings for the rotor and elastic centering portions rigidly attached theretoand having outwardly facing bearingpoints in engagement withlthe interior' CLARENCE CORBIN MITCHELL. Witnesses:

W. BUeI-IANAN, JOSEPH I. VVHITE. 

